Generating Average From Group Of Numbers In List That Match Two Criteria?

So we had a month long, company paid (woohoo!) "weight watchers" challenge. On 1 worksheet ("Stats"), I have the Name of every Employee (A Column), then their Start Weight (B Column), End Weight (C Column), Department (D Column) and finally Location (E Column).

I know how sensative some people can be about their weight, so I locked the page and created another worksheet named "UI", which will display the "Average End Weight" for each department. So Human Resources would be the department in cell A2 on the UI sheet, with City 1 being the Column Header in cell B1. There are 8 cities (offices) and 23 departments.

So, for cell B2, I want to scan through the "Stats" worksheet and locate all of the cells in the department and location columns that read "Human Resources" and "City 1" respectively. Then grab the "End Weight" for every row that meets these 2 criteria, add them up, and divide by the number of "End Weights" that were grabbed.

My solution would be to make a separate column for each department (and then each city, so essentially 8 columns to represent all the cities for each department), use a nested (maybe 4) IF statements to then list only the end weight if that particular row meets the criteria, then at the bottom of each separate column, add all the shown numbers up and divide, then draw the information from THAT number into the "Average" cell on the UI worksheet. But it isn't very dynamic and if i want to use this sheet next year, there will be more employee info to be added and it would be a mess..further more, it would be...what...23 Departments x 8 Cities x 155 employees = ~28,500 added cells.